A horrific local crime has again shown the folly of allowing a monopoly on providing the service of justice. A monopoly which arose, not by providing a superior service no one could beat, but imposed through destructive laws.
A monopoly in the free market, even one which provides an exceptionally superior service or product, is always temporary. As soon as someone believes they can do it better, spurred on by the potential profits, they will try, and no one can prohibit their attempt.
True monopolies can only survive when enforced by "laws" which forbid- or heavily regulate- competition. An enforced monopoly never results in the best you can get for your money. When such a monopoly administers something as crucial as justice, it is especially tragic.
Maybe police employees really are the most qualified to investigate and try to solve crimes, but to enforce made up rules granting them monopoly status over an investigation helps no one but themselves. Well, and perhaps the more than 30% of murderers who are never caught.
You might point out that private investigators exist, but the truth is they are not really allowed to compete with the police; only to supplement them while remaining subservient. They are supposed to defer to the police and are forced to either dig up information the police have not found first and squirreled away, or beg the police for scraps. They are always expected to hand over, to the officials, anything they find. If a private investigator discovered critical evidence and refused to share the new data with the police, he would probably be charged with a crime. When police do the same thing, people think it's normal.
Independent individuals who discover evidence missed by the "professionals" are eyed with suspicion, and are required to hand over all evidence to the police, who act, not as a voluntary centralized clearinghouse, but as a jealous miser, insisting no one else has the right to the information they hold for themselves. If finding those responsible were the highest priority, this wouldn't be the way to go about it.
Police and government officials also assert they are the only proper ones to release information or to speak publicly about a case.
When a group claims exclusive authority over some necessary service, efficiency is compromised, delays result, and people suffer. If justice, whatever you believe justice to be, were the real goal, you would have as many different investigations going on, and sharing information, as there were people interested in solving the case. No one would be allowed to monopolize the investigation to the detriment of truth and justice.